Premium
Functional characterization of the A spergillus nidulans glucosylceramide pathway reveals that LCB Δ8‐desaturation and C9‐methylation are relevant to filamentous growth, lipid raft localization and Ps d1 defensin activity
Author(s) -
Fernandes C. M.,
de Castro P. A.,
Singh A.,
Fonseca F. L.,
Pereira M. D.,
Vila T. V. M.,
Atella G. C.,
Rozental S.,
Savoldi M.,
Del Poeta M.,
Goldman G. H.,
Kurtenbach E.
Publication year - 2016
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13474
Subject(s) - biology , sphingolipid , mutant , virulence , galleria mellonella , biochemistry , microbiology and biotechnology , aspergillus nidulans , gene
Summary C8‐desaturated and C9‐methylated glucosylceramide (GlcCer) is a fungal‐specific sphingolipid that plays an important role in the growth and virulence of many species. In this work, we investigated the contribution of Aspergillus nidulans sphingolipid Δ8‐desaturase (SdeA), sphingolipid C9‐methyltransferases (SmtA/SmtB) and glucosylceramide synthase (GcsA) to fungal phenotypes, sensitivity to Ps d1 defensin and Galleria mellonella virulence. We showed that Δ sdeA accumulated C8‐saturated and unmethylated GlcCer, while gcsA deletion impaired GlcCer synthesis. Although increased levels of unmethylated GlcCer were observed in smtA and smtB mutants, Δ smtA and wild‐type cells showed a similar 9,Me‐GlcCer content, reduced by 50% in the smtB disruptant. The compromised 9,Me‐GlcCer production in the Δ smtB strain was not accompanied by reduced filamentation or defects in cell polarity. When combined with the smtA deletion, smtB repression significantly increased unmethylated GlcCer levels and compromised filamentous growth. Furthermore, sdeA and gcsA mutants displayed growth defects and raft mislocalization, which were accompanied by reduced neutral lipids levels and attenuated G. mellonella virulence in the Δ gcsA strain. Finally, Δ sdeA and Δ gcsA showed increased resistance to Ps d1, suggesting that GlcCer synthesis and fungal sphingoid base structure specificities are relevant not only to differentiation but also to proper recognition by this antifungal defensin.